Gonadotropins were measured in rhesus monkey fetuses from days 60 to 150 of gestation. The rhesus fetus contains immunoreactive LH plus FSH that is low and unchanging with time of gestation in males, but is high in females. Bioactive LH showed similar differences between male and females. These results suggest early development of feedback relationships between secretions of the fetal testes and the hypothalamic-pituitary axis. The fetal ovary shows little steroid production probably because it does not contain a gonadotropin receptor reflected by its inability to respond to exogenous gonadotropin.